Foundation installation in Redwood City CA - built on ground that's checked first

Most people who call about a foundation are planning an addition, a backyard unit or a new building, and everybody pictures the concrete. Concrete does exactly what the ground under it does, just slower, so the ground is where I start. The price moves with the size of the footprint, how much soft soil has to come out, how steep the lot is, how easy it is to get trucks in and what the engineer calls for in the plan. The schedule turns on whether a site study comes first, how long any permit takes and the weather on pour day. Your own figure comes from the estimate I write up after I've walked the lot.

Before I plan anything, I check with you whether your lot sits in a mapped hazard zone, because that can mean a site study comes first, and then we build to what the engineer recommends. Our crew digs out to the depth the plan calls for, pulls out the soft dirt and packs the subgrade, the soil the concrete sits on, in layers so it doesn't settle later. We check where the water runs so it moves away from the house, set the forms and tie the rebar, the steel inside that holds the concrete together when it's under load. We pour early in the day so the heat doesn't leave a weak top, then finish it and let it cure, which is the slow hardening that gives concrete its strength. If the budget gets tight, the base is the last thing I'll cut, because you can fix a rough edge later but you can't fix bad ground with a house sitting on it.

A foundation usually comes with more concrete around it. On most jobs the concrete footings that spread the weight into firm ground get poured as part of the same work. On commercial lots, a new building needs somewhere to park, and concrete parking lot building uses the same ground prep on a bigger scale.

Parts of California are mapped as hazard zones, and when a lot sits in one, the city or county has to require a site-specific investigation before it issues most building permits. Weak soil or rock under a lot can give way in an earthquake, so a state-licensed engineering geologist or civil engineer studies the ground and recommends what the job needs, and we build to that. San Mateo County's liquefaction and shaking maps show risk by neighborhood, not for your lot, so treat them as a reason to look closer rather than an answer. On steep hillside lots, the county's safety report says a single flat pad doesn't work, and building there takes substantial grading and retaining walls. Permits in the city go through the Redwood City Building Department, and whether your foundation job needs one is something I'll tell you at the estimate. If it does, we handle the paperwork and inspections with the city or the county.

Around here we build on everything from flat lots down toward the Bay to lots that climb into the hills, and the two ask for very different groundwork. We see the same range on jobs in San Carlos and Belmont, so on every one of them I look at the ground before I think about forms.